Trajectory of geographic occupancy an informative predictor of extinction risk in fossil microplankton taxa

While standing geographic occupancy (range) is often acknowledged as an important factor in determining a taxon’s extinction risk, the trajectory of geographic occupancy through time is not always considered. The extinction risk of four major microplankton groups— foraminifera, calcareous nannofossils, radiolarians, and diatoms— were examined with respect to their geographic range and the temporal trajectory of their geographic range. Each data set, which ranged from approximately 100,000 to 250,000 occurrences, was downloaded from the Neptune Sandbox Berlin database. Completeness metrics were calculated to determine the “gappiness” of each data set, and our findings showed comparable completeness values for each collection of data. Using logistic modeling, the relationship between occupancy, occupancy change, and extinction risk were explored for each microplankton group. Model coefficient ratios and the proportion of total deviance reduction attributable to each term were calculated for each data set. Our findings suggest that change in geographic occupancy through time can account for up to 37% of gross extinction risk. Additionally, the change in geographic occupancy through time is nearly 5 times more informative in siliceous microplankton than in calcareous microplankton. We suggest that the more opportunistic life mode of siliceous microplankton could influence this pattern. The fact that geographic occupancy trajectory can be used as an informative predictor of extinction risk demonstrates the benefit of incorporating paleontological data into modern conservation efforts.